On road theft from tractor-trailer rigs and other cargo vehicles has been an ongoing problem. Tractor-trailer rigs present tempting targets to criminals due to the large quantity of high-value cargo they contain. A popular point of access on a trailer is through the rear roll-up doors, which have locks that are often easily breached or removed. One such easily breached lock type is the Truk-Lok II made by Babaco Alarm Systems, Inc. This type of lock is ubiquitous and a common method of breaching this lock is to slide a jacking device beneath the roll up door and apply upward force with the jack until the lock breaks at its failure points.
U.S. Pat. No. 3,893,722 issued to Galbreath et al. discloses a lock assembly wherein a hand lever operates an arcuate latch hook which engages a catch pin. The hand lever is elongate and spans across a distance to a separate key-lock assembly which locks the lever in place. A drawback to this design is that the hand lever can be sawed in half, thus freeing the hand lever from the lock assembly to allow the cargo door to be opened. Other designs merely padlock the hand lever in place; however these designs are easily breached by defeating the padlock.
Therefore a need exists for a locking device for roll-up doors on tractor-trailer rigs or other cargo vehicles which can resist forcible breaches from jacks, crow-bars or other force application tools placed beneath a roll-up door. A need further exists for a locking device which cannot be breached by merely freeing the hand lever of a locking device.
The foregoing reflects the state of the art of which the inventor is aware, and is tendered with a view toward discharging the inventor's acknowledged duty of candor, which may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing discussion does not teach or render obvious, singly or when considered in combination, the inventor's claimed invention.